Field of the Invention
The present invention relates to a fixing apparatus used in an image forming apparatus that employs an electrophotographic or electrostatic recording image forming process, such as a copying machine, a laser beam printer, and a light-emitting diode (LED) printer.
Description of the Related Art
A fixing apparatus using a film is known as a fixing apparatus included in an electrophotographic or electrostatic recording image forming apparatus. The fixing apparatus includes a cylindrical film and a heater which makes contact with an inner surface of the film. The fixing apparatus fixes a toner image formed on a recording material to the recording material by using heat of the film.
Since the film has a small heat capacity, the fixing apparatus has an advantage of short warm-up time. However, when performing continuous fixing processing on small-sized recording materials, the fixing apparatus is more likely to cause a temperature rise of a non-sheet passing portion. The temperature rise of a non-sheet passing portion refers to a phenomenon where the temperature of the non-sheet passing portion, which is a region where no recording materials pass, rises excessively. Japanese Patent Application Laid-Open No. 11-260533 discusses an apparatus in which a long narrow aluminum plate is longitudinally put in contact with a heater so that the movement of heat of a non-sheet passing portion is promoted to suppress the temperature rise of the non-sheet passing portion.
However, the metal plate discussed in Japanese Patent Application Laid-Open No. 11-260533 is formed in a long narrow shape (an aluminum plate with a length of 230 mm, a width of 10 mm, and a thickness of 1.0 mm) according to the size of the heater. The metal plate is thus prone to warping, which can affect the adhesion of the metal plate to the heater. To suppress the warpage of the metal plate, the metal plate may be configured to be longitudinally divided in a plurality of parts. However, there is a problem that the movement of heat by the metal plate between a central portion and ends can be hindered depending on how the metal plate is divided.